Molding apparatus

ABSTRACT

A mold, which can be advantageously used for foam molding articles, has a bottom box with a cover. Means, such as locating pins are provided for supporting profiled bars which remain in and reinforce the molded article, drive means being provided for moving the mold box cover between a first position in which the cover closes said mold box and a second position in which the mold box cover lies displaced from said mold box in a mold open position.

D United States Patent 1151 3,642,398 Von Rudgisch 1 1 Feb. 15, 1972 [54] MOLDING APPARATUS 3,139,649 7/1964 Leech ..l8/16 T 2,630,614 3/ 1953 Peterson 249/96 X [721 Invenmrg f f f gif 'ffg Chmkelsmssm 2,373,799 4/1945 Wilson ..18/16 R x e Y 3,513,506 5/1970 Meingast ..18/16 T x [22] Filed: June 17, 1970 1,133,223 3/1915 Binning.... ....i249/154 X 2,783,501 3/1957 Kutik ..l8/2 RP UX 1 PP 46,971 2,558,026 6/1951 Wilson. ..l8/2 RP ux 3,462,776 8/1969 Cox ..249/142 UX 30 Fore A lication Priorit D ta 1 y a Primary Examiner-H. A. Kilby, Jr.

June 19, 1969 Germany ..P 19 30 983.2 Angrney- Bums, Doane, Swecker & Mathis Nov. 28, 1969 Germany ..P 19 59 765.0

[57] ABSTRACT 5 .S.Cl .425 117 49 l 4,4 5 4, I 2} U 425/84 7 3 4252/4114 A mold, which can be advantageously used tor foam molding [51] Int. Cl "1329c 3/02 articles has a bottom box with a cover Means such as lucat' 581 Field 61 Search ..18/16 R, 16T, 16 F, 30 LM, ing P? are P Summing l bars whlch 18/30 LD 30 LT 2 249/85 96 154 142 remain 1n and relnforce the molded article, drive means being provided for moving the mold box cover between a first position in which the cover closes said mold box and a second [56] References cued position in which the mold box cover lies displaced from said UNITED STATES PATENTS mold box in a mold open position.

3,140,654 7/1964 Jewett ..18/16 T 28 Claims, Drawing Figures 27 30 20 27 if I l 1'' I f 111:1. l I 1 I 28 G: 48 l lt H1 111' 19 5 I :1 T H '0 I l l l f l l 1] l I l l 1, I I I I l a I 1 ll '1 l PATENTEUFEB 15 I872 SHEET OlUF 12 v Jtflhrif r w IIIL 51mm M KQDGISCH, IN VEN roR h is PAIENTEDFE 15 I972 SHEET UEUF 12 3 GM m RUJTGIXCHI INVENTOR BY WJ HKQM SHEET 03 0F 12 EHQAQ m Rim/5m, NvENmR BY W m w PATENTEDFEB 15 1972 'IIIIIIIIIJHIIIII llllll 7O IIIIIWKIIITII llll.

mum 15 m2 SHEET UQUF 12 mm m fibGlscH, INVENTOR PATENTEDFEB 15 I972 SHEET 05 0F 12 FIG. 7

ace/M m R Oncvlscw INVEN TOR PATENTEDFEB 15 I972 v 3. 642 398 sum 06 0F 12 BMW M fiiibclsm; INVENTOR AA o'Hror n27 PATENYEHFEB 151912 3.642.398

SHEET OSUF 12 744 4 FIGJG EDGAR m RUQGISCH, 'INVENTOR PATENTEDFEB 15 I872 3, 642. 398

SHEET llUF 12 FIG 25 Elm WK m RUM/mu, INVENTOR AA N MOLDING APPARATUS The present invention relates to a molding apparatus and also relates to a device by which, during molding, inserts, inlays, reinforcing profiled bars, dies, etc., are brought into, and retained in, a specific position relative to the part to be molded.

The molding apparatus constructed in accordance with the invention is suitable for molds and molding processes of any kind. However, it is used especially in the case of mold foaming articles such as chairs as disclosed in the applicants copending application No. 46,064, filed June 15, 1970 (based on German Pat. applications No. P 19 30 583.0 filed June 16, I969 and No. P 19 61 153.1 filed Dec. 5, 1969) and will be explained with reference to such a mold. In mold foaming, chemical agents are introduced into a mold. The foams involved are forexample plastics material foams based on polyurethane, polystyrene, polyvinyl chloride, urea formaldehyde, phenol formaldehyde, latex, etc. They expand in the mold and form a foamed article the consistency and hardness of which is determinedby the nature of the chemical agent and the shape ofwliich is determined by the dimensions and shape of the mold and any dies placed therein.

This mold foaming process, which takes place on a chemical basis, does not constitute any part of the invention. However, it is explained here to the extent necessary for understanding the molding apparatus constructed in accordance with the invention. The mold comprises a mold bottom box and box cover. The two parts have specific dimensions and a specific shape. Dies are placed into the mold bottom box when the mold is open. The inside of the mold is treated with an antiadhesion agent.

The mold is subsequently closed by placing the box cover onto the mold bottom box and pressing it thereagainst with a specific force. The chemical agents are injected into the mold through a valve in the box cover. The chemical agents expand in the mold, fill the mold and harden. The mold is opened after a specific time required for hardening. The finished article of foamed material is removed. The mold is prepared for the next foaming operation and the entire process is repeated.

In accordance with the prior art, the operations described above are carried out manually. This means that the box cover is placed onto the bottom box manually, the clamping and holding devices are mounted and locked manually in order to retain the box cover on the bottom box during the foaming operation, these devices then being released manually in order to remove the box cover manually. It is obvious that these manual operations require personnel and time and do not permit a rapid operating rhythm.

The present invention seeks to provide an apparatus on which these operations are carried out mechanically and automatically and thus more rapidly and more accurately.

Furthennore, in accordance with the invention, the apparatus is constructed so that inlays, inserts, dies, or the like, are held in specific positions in the mould during the mold foaming operation. Furthermore, the mold is provided with means by which through bores, etc., are provided in the article to be molded. The invention also seeks to simplify, expedite and mechanise the opening of the mold and the removal of the finished molded articles from the mold.

Proceeding from an apparatus having a stand, a mold bottom box which can be mounted onto the stand, and a box cover which is placed onto the bottom box, the invention provides a vertical guide which is formed on the stand, the box cover is held in this vertical guide, and a drive device is provided for the box cover in order to displace the box cover in the vertical guide or to move the box cover towards the bottom box into a closed position and away therefrom into an open position and to retain the box cover in these two end positions.

Thus, in accordance with the invention, the mold is opened and closed by a mechanical drive means. The activity of the personnel is limited to putting the drive means into operation by pressing a button, throwing a switch, or the like. Thus, the

invention renders possible a great saving in personnel, reduces the demands on the physical strength and the carefulness of the personnel, and renders possible more rapid and more accurate work or a higher rate of molding.

In accordance with the invention, the construction of the vertical guide is such that the stand has vertical hollow supports in which rods are guided, the top ends of the rods being connected by a frame, and the box cover being secured to this frame. Advantageously, the box cover is interchangeable, so that no difficulty is involved in changing over to other molds.

In accordance with the invention, a frame is provided at about half the height of the hollow supports in a convenient operation position. This frame connects the hollow supports and has holding devices which receive the mold bottom box in an interchangeable manner. This ensures that, in order to change the molds, a bottom box may also be readily interchanged with a bottom box of different dimensions and size.

Furthermore, in accordance with the invention, lazy tongs are hinged to the two sides of the frames and interconnect the latter, one bar of each lazy tong being connected to the drive means. In particular, one end of one bar of each lazy tong is hinged to the bottom and top frame respectively and a horizontal guide is provided on the bottom and top frame respectively for the other end of each bar, the horizontally displaceable bottom ends of the bars being interconnected by a rod which is actuable by the drive means.

In accordance with the invention, the drive means is effective in both directions of movement and is advantageously in the form of a double acting pneumatic cylinder. If compressed air is not available at the place where the apparatus is operated, a hydraulic cylinder or an electrical or electromagnetic drive or any other drive device may be used without departing from the scope of the invention.

The bars of the lazy tongs are pulled towards one another or raised when the drive means is operated in one direction. The top frame including the box cover is then moved away from the bottom frame including the bottom box and the mold is thus opened. The bars of the lazy tongs are spread apart when the drive means moves in the other direction. The box cover is thus moved towards the bottom box and is finally pressed thereagainst. The mold is then in its closed or operating positron.

In accordance with the invention, a flap is arranged at one end of the bottom box in a manner known per se, so that the bottom box is easily accessible and may be operated from the front. In accordance with the prior art, this flap is opened and closed manually. When closing the flap, care must be taken that the front edge of the box cover overlaps this flap. In order to open and close the flap mechanically, and in accordance with the invention, the flap is arranged at the end located between the fixedly hinged bottom ends of the bars, the bottom end of the flap being hinged and its top end being connected by links to the bars the bottom ends of which are hinged to the bottom frame adjacent the flap. During the opening and closing movements of the mold, the pivoting movement of these bars includes a horizontal movement component which extends in the same direction as required to open and close the flap. By connecting the flap to these bars, this movement is transmitted to the flap, so that the latter is automatically moved in the opening direction or closing direction.

In accordance with the invention, these links are levers, one end of each lever being hinged to the flap and the other end being provided with a slotted hole, a pin being provided on each bar and each slotted hole being guided over a pin.

The pins mounted on the bars transmit the movement to the links. The slotted holes effect a lost motion at the commencement of the opening movement. Thus, the flap may be pivoted into its open position only after its top end has been removed from the box cover which overlaps the flap when the flap is in its closed position.

The pressure occurring during the molding operation can increase to the extent where the box cover is lifted from the bottom box and is no longer retained in its closed position by the pneumatic cylinder. In order to prevent the box cover from opening in this undesired manner, and in accordance with the invention, hooks open at the top are mounted on the top frame, and latches which are connected to the hollow supports or to the bottom box are engageable into, or may be hooked into, the hooks. Thus, the box cover is retained on the bottom box.

On the other hand, it is possible for the foamed molded article to be so strongly bonded to the bottom box and to the box cover that the latter cannot be opened solely by the pneumatic cylinder, i.e., the mold sticks together." In this case, the invention provides the possibility of momentarily applying an additional force by a simple arrangement in order to open the mold and to detach the box cover from the molded article or from the bottom box.

For this purpose, and in accordance with the invention, a projecting cam is provided laterally on each side of the top frame or of the box cover, and a cam plate is rotatably secured to each traverse and, when turned, slides under the cam and raises the latter.

In accordance with a further embodiment of the invention, the cam plates are actuated manually. For this purpose, the front end of each cam plate merges into a rod, the rods on the two cam plates being interconnected by a transverse rod. The cam plates are turned below the cams and the mold is opened when the transverse rod is depressed or pulled down abruptly.

In accordance with the invention, the cam plates or the transverse rod when in the normal position are always in a position in which normal operation is not obstructed. In particular, each cam plate is biassed by a spring which turns the cam plate into a position in which the transverse rod is pivoted upwardly.

It has already been mentioned that the mold is opened and closed preferably by a pneumatic cylinder. The pneumatic cylinder must apply not only dynamic forces, i.e., forces for opening and closing the mold, but also apply static forces. For example, the mould must be retained in its closed position against the internal pressure which occurs during molding. Furthermore, a particularly great force has to be applied at the commencement of opening the mold, since the mold bottom box and the box cover are held together by the molded article or they stick together.

The present invention seeks to solve the problem of constructing the molding apparatus such that particularly great forces are available, at the commencement of opening the mold and for the purpose of holding together the box cover and the bottom box when the mold is in its closed position. It is not intended to solve this problem by increasing the size of the piston face, since this would increase the dimensions, the weight and the cost of the pneumatic cylinder and also the size of the pressure medium source. The invention seeks to solve the problem by an advantageous arrangement of the pneumatic cylinder with the piston rod and by connecting the piston rod to the lazy tong bars in an advantageous manner, the desired result being obtained by the skilled utilization of the laws of leverage.

For this purpose, the pneumatic cylinder and its piston rod are arranged parallel to the rod which connects the bottom displaceable ends of the bars, the piston rod being connected to one end of each of two levers, and the other ends of these levers being hinged to the bottom frame or toe the rod connecting the bottom ends of the bars, so that this rod is pushed away and the mold is closed when the piston rod is extended, and is pulled in and the mold is opened when the piston rod is retracted into the pneumatic cylinder.

The leverages can be varied within wide limits and adapted to requirements by the selection of the length of the two levers which are acted upon by the piston rod.

Advantageously, the arrangement is such that the two levers are located in alignment with each other and at right angles to the piston rod when the piston rod is extended when the mold is in its closed position.

In this embodiment, the pneumatic cylinder does not have to apply the closing pressure for the mold. Closing pressure" is intended to mean that the mold has to be retained in its closed position against the internal pressure occurring during the molding operation. This internal pressure seeks to lift the box cover and thus displace the rod which connects the bottom ends of the bars. Thus, the rod is acted upon by a force which is transmitted to the two levers which are in alignment with one another and at right angles to the piston rod when the mold is closed. This means that the force has no components acting in the direction of the piston rod. Thus, no forces act upon the pneumatic cylinder and it is unnecessary to maintain the latter under pressure. The force exerted upon the levers by the rod is transmitted by the levers to the bottom frame. This means that the forces occurring in the mold during the molding operation are absorbed in the frame of the apparatus itself.

In accordance with the invention, the pneumatic cylinder is suspended on two bars, one end of each bar being hinged to the pneumatic cylinder and the other ends of the bars being hinged to the outer ends of the levers and thus to the bottom frame or to the rod which connects the bottom ends of the bars. Thus, the pneumatic cylinder is displaceable in the molding apparatus and is not rigidly mounted therein. The bottom box. and a box cover basically comprise a bottom box base and a box cover top respectively, and four sidewalls. However, according to the molded piece to be manufactured, it may be desirable for the molded piece to be freely accessible from one or from two specific sides when the mold is open. This means that the sidewalls on these sides have to be attached to the box cover so that they are moved upwardly when the mold is opened and expose the molded article.

To solve this problem structurally, and in accordance with the invention, the bottom box and the box cover each comprise a bottom or a top wall and two sidewalls, the sidewalls being secured at opposite sides on the bottom box and the box cover respectively, so that the sides of the molding box are alternately enclosed from the top and the bottom by a sidewall.

For the purpose of guiding and reinforcing the sidewalls, so that they can withstand the pressure occurring during foaming, a reinforcement or a stiffening is provided on the bottom box base and on the box cover top at the sides of the bottom box and the box cover not closed by a sidewall, and overlaps the associated sidewall and when the mold is closed.

It has already been mentioned that, due to the great molding pressure, the foamed article adheres so firmly to the mold after the molding operation that special measures have to be taken in order to release it from the mold. In order to release the foamed article from the mold in a simple manner, or to remove it from the mold, lifting or removing plungers are reciprocally arranged in the bottom box base. The molded article is lifted out of the mold by means of these plungers.

One or a plurality of these lifting or removing plungers are arranged at each corner of the mold as required and, for the purpose of actuating them, they are inserted into spindles which are guided in vertical guide bushes and which are coupled to a drive. They serve as cores and form cavities in the molded article. However, it is not known to construct such spindles so as to be displaceable and driveable such that they serve to remove the molded article from the mold.

In accordance with the invention, the spindles are threaded and are provided with sprocket wheels. The sprocket wheels of all the spindles are interconnected by a chain which is movable by a ratchet which may be mounted on one of the spindles. Alternatively the chain may be driven by connecting it to a pneumatic cylinder.

The spindles and the sprocket wheels intermesh by means of flat-topped threads. In specific cases, the removing plungers or the spindles acting on one side of the foamed article, or on the bottom or the top of the foamed article, have a different pitch from the other two spindles. This means that the spindles turn in pairs at different speeds. Thus, the foamed article is lifted more rapidly at one side or at one end than at the other side or the other end. In other words, the foamed article is lifted and tilted simultaneously, thus facilitating its release from the mold.

Certain foamed articles have to be freely accessible virtually from all sides. In the case of such foamed articles, and in accordance with the invention, the box cover is closed on three sides and the bottom box has vertical guides on the free side of the box cover for the purpose of inserting a sidewall. Thus, in this embodiment, the foamed article is exposed in the bottom box when the mold is open, since three sidewalls have been removed upwardly together with the box cover and the fourth sidewall can be withdrawn from the guides on the bottom box.

For the purpose of reinforcing certain foamed articles, such as frame-shaped seats or backs for furniture, they are stiffened by metal reinforcing profiled bars which are incorporated in, or foamed into, these articles. The reinforcing profiled bars have to be held in specific'positions in the mold. The reinforcing profiled bars are also frequently provided with threaded bores which have to be kept free from foam materials. These threaded bores may be used for screwing in threaded pins or lugs which retain the bores and the reinforcing profiled bars in the desired position. In particular, and in accordance with the invention, spindles are vertically guided in the bottom of the mold bottom box, their top ends being provided with threaded lugs, and they are arranged so that the threaded lugs engage into corresponding threaded bores which are provided in the reinforcing profiled bars which are placed into the mold.

The portions of the spindles located in the molding box are smooth and cylindrical. The spindles are coupled to a drive of the kind already described by means of sprocket wheels, a chain, and ratchets, so that the spindles can be moved up wardly and downwardly.

The centers of the above-mentioned frame-shaped seats and backs are provided with openings. During the foaming operation, these openings are formed by appropriate cores or inserts which are placed in the mold bottom box. In accordance with the invention, an insert having a shape corresponding to an opening to be formed in the foamed article is placed onto the bottom wall of the molding box, the insert has bores into which pins are insertable to form holes in the foamed article, i.e., in the seat or in the back.

The pins are inserted into the mold for the molding operation and are withdrawn again after the molding operation or operations. These pins virtually constitute cores. To move the pins rapidly inwardly and outwardly, the pins are guided in guide bushes which are secured on the inside of the insert, the inner ends of the pins are hinged to two-arm levers, one end of each lever being pivotably held in a support on the bottom of the mold bottom box, and the free ends of the two-arm levers are provided with a handle.

In a further embodiment of the invention, levers in alignment with one another on one side of the insert are interconnected by a connecting rod which is in the form of a common actuating handle for all the levers.

In a modified embodiment, the levers are pivotable in a horizontal plane about a vertical axis.

If cushions or padding of soft foam are to be foamed on the molding apparatus constructed in accordance with the invention, it can be advantageous to provide cavities in the centers of these cushions. These cavities provide a twofold advantage. One advantage resides in the fact that less raw material is required, since the cavities are filled with air instead of foam. The second advantage is that the resilience of such a cushion is increased, since the hollow airspaces can be compressed more readily than the foam material.

For the purpose of manufacturing such a cushion, the invention provides an embodiment which includes oval dies which are arranged substantially in the center plane of the mold and which are held on rods on the bottom box and/or on the box cover. Hitherto such cushions having airspaces have been manufactured by providing cavities in one side of two cushion halves and glueing the two cushion halves to one another. This method of manufacture is complicated and, in addition to this, the adhesive layer has reduced the resilience of the cushion.

In accordance with the invention, these dies are uniformly distributed. Preferably, rows of dies are secured alternately to the bottom box and to the box cover, the dies in adjacent rows being staggered.

The invention will now be further described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a side elevation of one embodiment of a molding apparatus constructed in accordance with the invention, illustrated in a closed or retracted position, 7

FIG. 2 is a rear elevational view of the apparatus of FIG. I seen in the direction of the arrow 11 in FIG. 1,

FIG. 3 is a side elevation of a molding apparatus constructed in accordance with the invention, illustrated in an open or extended position,

FIG. 4 is a side elevation similar to FIG. 1, illustrating a locking device of the mold in the closed position and the arrangement by which the box cover is released from the bottom box,

FIG. 5 is a side elevation of a different embodiment of molding apparatus in which the mold is open or the box cover is raised,

FIG. 6 is an inverted plan view, seen in the direction of the arrow 6 in FIG. 5, of the pneumatic cylinder, the levers, the

bars and the displaceable rod, the mold being open,

FIG. 7 isa view corresponding to FIG. 6, but the mold being illustrated in its closed position,

FIG. 8 is a perspective illustration of a particular embodiment of the bottom box and of the box cover,

FIG. 9 is a section through the bottom box with the box cover in an open position, with inserted cores for molding or foaming the frame-shaped back for a chair or the like,

FIG. 10 is a section through a mold corresponding to FIG. 9, the mold being in a closed position after foaming the frame of the back from rigid foam,

FIG. 11 is a section, corresponding to FIG. 10, through a further mold used during the foaming operation, after foaming a layer of semirigid foam onto the frame of the back made from rigid foam,

FIG. 12 is a section, corresponding to FIG. 11, through the next mold used during the foaming operation, after foaming soft foam onto the rigid foam elements and the semirigid foam layer of the back illustrated in FIG. 11,

FIGS. 13 to 17 are diagrammatic illustrations of various embodiments of a back, for a chair or the like, manufacturable on the apparatus constructed in accordance with the invention,

FIG. 18 is a diagrammatic, exploded illustration of a specific embodiment of a bottom box cover with an insert placed in position for manufacturing a back,

FIG. 19 is a view seen in the direction of the line 19-19 in FIG. 18,

FIG. 20 is a section through the bottom box, shown in Fig. 18, with the box cover mounted thereon, especially illustrating the pins which are insertable into a molded article,

FIG. 21 is a plan view of a further embodiment of the bottom box, especially illustrating the pins which are insertable into the molded piece,

FIG. 22 is a section taken on the line 2222 in FIG. 21,

FIG. 23 is an inverted plan view of a box cover along the line 23-23 in FIG. 24, especially illustrating the oval dies which are secured to the bottom box, and which are not visible, being illustrated by dash-dot lines in order to provide a complete picture,

FIG. 24 is a schematic section through an open mold after foaming a cushion from soft foam, especially illustrating the oval dies and the cavities formed in the cushion, and

FIG. 25 is a diagrammatic, perspective illustration of a threaded sleevelike member which may be incorporated in a molded piece.

Referring now to the drawings, and particularly to FIG. I, a molding apparatus is illustrated which is carried by a stand 10. The stand comprises four hollow supports 12 which are welded onto a baseplate 14. A bottom frame 16 is arranged at about half the height of the supports 12 and is connected to the supports 12. Rods 18 are telescopically received in the four supports 12 and carry a top frame 20 which also holds the rods together. Cross-beams 21 extend invthe frame 20, the cross section of the cross-beams being illustrated diagrammatically in FIGS. 1 and 3. A mold bottom box 22 is located above the bottom frame 16. Base bars 24 extend below the bottom of the bottom box and are held in pockets 26. The pockets 26 are secured on the bottom frame 16. A flap 28 is secured to the front end (on the left in FIGS. 1 and 3) of the bottom box 22. A mold box cover 30 is located below the top frame 20 and is held thereby. For this purpose, the box cover 30 is hung into the cross-beams 21 and locked thereto.

A lazy tong 32 is arranged on each side of the apparatus. Each lazy tong 32 comprises a bar 34 and a bar 36. The ends of the bars 34 and 36 located on the left in FIGS. 1 and 3 are hinged to plates 38 which are secured to the bottom frame 16 and the top frame 20 respectively. The right hand ends of the bars run in horizontal guides. The horizontal guides are formed by U-shaped bar sections 40 and 42. The displaceable bottom ends of the bars (located on the right in FIG. 3) are connected by a rod 44. The entire length of the rod 44 is illustrated in FIG. 2. The ends of the rod 44 carry rollers 46 which run in U-shaped guide bar sections 42. Correspondingly, rollers 46 are secured to the top, movable ends of the bars and run in the U-shaped bar sections 40 (FIG. 3). The bars 34 and Compressed air is fed to the pneumatic cylinder 52 by way of the two air lines 58. The pneumatic cylinder 52 depends from a projection 62 where it is attached by a hinge 64. Thus, the pneumatic cylinder is capable of limited pivotable movement. This pivotable movement is necessary since the piston rod 54 does not extend parallel to the bottom guide or the U-shaped bar sections 42. Of course, this is not essential to the invention, since it is also possible to secure the pneumatic cylinder 52 parallel to the horizontal guide.

A pin 66 is secured to the outside of each bar 36, one of these bars being visible in FIG. 3. The pin 66 is in operative connection with a bar 68. A bar 68 is provided on each side and its left-hand end is hinged to the flap 28, while the righthand end of each bar 68 is provided with a slotted hole 70 into which a pin 66 engages.

A working cycle of the apparatus described above will now be described:

The end of the pneumatic cylinder 52 located on the right in FIGS. 1 and 3 is actuated by compressed air. The piston rod 54 is retracted and displaces the rod 44 towards the left (direction of view towards FIG. 3). Thus, the lazy tongs 32 are raised and the mold is opened. The mold moves from the closed position illustrated in FIG. 1 into the open position illustrated in FIG. 3. The fully open position is reached when the piston rod 54 has been fully retracted. During this movement, the arms 36 pivot in the counterclockwise direction. The pins 66 are moved towards the left and are pressed against the left-hand ends of the slotted holes 70, so that the flap 28 is pivoted upwardly. When the' mold is closed, the top end of the flap 28 extends into the box cover 30, as illustrated in FIG. 1. However, as is also shown in FIG. 1, the pins 66 run idly in the slotted holes 70 in the first instance and become effective only when they abut against the left-hand ends of the slotted holes. At this instant, the box cover 30 has been raised to the extent where the flap 28 is exposed.

The bottom box 22 and the box cover 30 are conveniently accessible when the mold is in the fully open position. They can be interchanged, cleaned, cores can be inserted, and they can be coated with an antiadhesive agent or a foamed article can be removed.

In order to close the mold, compressed air is admitted into the pneumatic cylinder in the other direction. The piston rod 54 travels towards the right into the closed position illustrated in FIG. 1. The flap 28 is pivoted upwardly and closed. The pressure in the pneumatic cylinder 52 is maintained when the mold is closed, thus resulting in a contact pressure by which the box cover 30 is retained in the closed position or pressed against the bottom box 22.

It will be seen that the entire apparatus operates automatically and the activity of the personnel is confined to pressing buttons or throwing a switch in order to admit compressed air into the pneumatic cylinder 52 in one direction or the other.

In addition to the parts already described, FIG. 4 illustrates hooks which are open upwardly and which are secured on the sides of the top frame below which the box cover is secured. Rings 82 engage into the hooks 80 when the mold is closed. The rings 82 are secured to levers 84 which are hinged to a traverse 86 on both sides of the mold. It may be seen that the rings 82 can be inserted into the hooks 80 and clamped simply by pivoting .the levers 84, thus locking the mold in its closed position. A cam plate 88 is pivotably mounted on the traverse 86 (on both sides of the mold). The cam plate engages below a cam 90 which is secured on the side of the top frame. The front end of the cam plate 88 is extended in the form of a tubular piece or lever to which a rod 94 is con nected. The rod 94 is removably connected to the lever 92. FIG. 4 shows the rod 94 on the side facing the viewer. A transverse rod 96 connects the rod 94 to the rod on the side remote from the viewer. When the transverse rod 96 is depressed, the cam plate 88 slides under the cam 90, presses the latter upwardly, and thus opens the mold. The length of the rod or rods 94 is such that the mold can be lifted by only slight force.

After the mold has been lifted, the latter is further opened by the pneumatic cylinder 52. In order to prevent obstruction of the work on the mold, the cam plate 88 is biased into the illustrated position by a spring shown in FIG. 4. The transverse rod 96 is pivoted upwardly when the cam plate is in this normal position. It is within the scope of the invention to connect the cam plates 88 to the pneumatic cylinder 52. If this connection is effected by a linkage and/or a cable, the pneumatic cylinder pivots the cam plates 88 at the commencement of the opening movement and thus lifts the box cover.

FIG. 5 illustrates a different embodiment of the invention in which a pneumatic cylinder 52 and its piston rod lie parallel to the rod 44 which connects the bottom ends of the bars 34 and which opens and closes the mold.

The pneumatic cylinder 52 is arranged substantially on a level with the bottom frame 16. The method of operation of this embodiment of the invention is illustrated in FIGS. 6 and 7. The pneumatic cylinder 52 acts by way of its piston rod 54. Pressure medium, preferably compressed air, is supplied to the pneumatic cylinder by way of air lines 58. A plate 202 is secured on the front end of the pneumatic cylinder 52. Bars 204 and 206 are hinged to the plate 202. Two levers 208 and 210 are hinged to the piston rod 54. The outer ends of the levers 208 and 210 are attached to plates 212 and 214 which are secured to the bottom frame 16 and the displaceable rod 44 respectively.

The bars 204 and 206 carry the pneumatic cylinder 54 which is suspended on the bars, the bar 204 being connected directly to the bottom frame 16 by the plate 212, and the bar 206 being connected to the bottom frame 16 by the plate 214 by way of the displaceable rod 44. The force exerted by the pneumatic cylinder is transmitted to the rod 44 by the levers 208 and 210. This will now be explained:

The initial position is assumed to be the open position illustrated in FIGS. 5 and 6. In order to close the mold, compressed air is admitted to the pneumatic cylinder so that the piston rod 54 is extended into the position illustrated in FIG. 7. Thus, the connection point between the two levers 208 and 210 (seen in the direction towards FIG. 6) is urged downwardly and the rod 44 is displaced towards the right;

Thus, the bottom ends of the two bars 34 are also displaced to the right in the U-shaped profiles 42 and the box cover 30 is lowered. The box cover 30 abuts se'alingly against the bottom box 22 when the box cover is in its lowest position. The position illustrated in FIG. 7 has been reached. The levers 208 and 210 are located in a straight line.

A great internal pressure occurs in the mold during the molding operation. This internal pressure seeks to open the mold and to raise the box cover 30. This means that a force directed towards the left acts upon the rod 44. This force passes through the levers 208 and 210 and finally acts upon the bottom frame 16 by way of the plate 212. This force has no components in the direction of the piston rod 54. This means that the pneumatic cylinder 52 may be left without pressure. This is a great advantage. The closing pressure also remains constant irrespective of whether the pressure in the pneumatic cylinder 52 is constant or is reduced by leading valves and the like.

The mold is opened by admitting compressed air into the pneumatic cylinder 52 in such a manner that the piston rod 54 is retracted. During this inward movement, the piston rod 54 turns the two levers 208 and 210 about their pivotal points on the plates 212 and 214. A great initial moment of stress occurs due to the fact that the piston rod 54 is located at right angles to the levers at the commencement of this movement. A mold is opened without effort, even when the molded article, the box cover and the bottom box have stuck together.

FIG. 8 illustrates a special embodiment of a molding box 100. The bottom box 22 and the box cover 30 are each provided with two sidewalls 102. The sidewalls 102 are located opposite each other in pairs. The molded article located in the bottom box is freely accessible from two sides when the box cover 30 is raised. When the mold is closed, the two sidewalls 102 of the box cover 30 are held by angular pieces 104 which are secured to the bottom of the bottom box. The corners of the molding box 100 are closed by angular pieces 106 which are secured to the top box of the mold.

A mold comprising a mold bottom box 22 and a box cover 30 illustrated in FIG. 8 is shown in an open position in FIG. 9. Compared with the illustration in FIG. 8, the bottom box 22 and the box cover 30 are each turned through an angle of 90. A female die 110 is located in the box cover 30, while male dies 108 and 112 are located in the bottom box 22. Guide bushes 116 are secured below the bottom 114 of the bottom box 22. Spindles 118 and 120 are guided in the guide bushes 116 so as to be nonrotatable. The spindles have flat-topped threads. It may be seen that the thread of the spindle 118 on the left is finer than the thread of the spindle 120. Plungerlike ejectors 122 are inserted into the spindles 118 and 120 from above. In the illustrated embodiment, the ejectors 122 have different diameters. The diameter varies from case to case, and is dependent upon the article to be molded. Sprocket wheels 124 are mounted on the spindles 118 and 120. A chain 126 passes around the two visible sprocket wheels 24 and around the two nonvisible sprocket wheels on the other side of the molding apparatus. A ratchet is mounted on one sprocket wheel and is rotated in order to turn its associated sprocket wheel 124. Thus, all the sprocket wheels 124 are turned and the ejectors are raised. The spindles 120 having a coarser thread will then turn more rapidly. Thus, the molded article (see the following FIGS. to 12) is raised more rapidly by the spindles 120 than by the spindles 118. Thus, in addition to its upward movement, the molded article will be tilted about its edge located on the left in FIGS. 10 to 12. Its left-hand inner edge will then tilt away from the left-hand vertical edge of the male die 108. Thus, friction between the molded article and the core is avoided at this place. The molded article can be released from the mold more readily. Alternatively, the chain 126 may be driven pneumatically or by an electric motor instead of being driven manually by a ratchet. A pneumatic cylinder 127 is illustrated in FIG. 9 by way of example. The cylinder 127 is secured to the stand of the molding apparatus and includes a pair of piston rods 129 which extend from each end of the pneumatic cylinder and are attached to the chain 126.

FIG. 10 illustrates a mold in the closed position after molding the frame-shaped back ofa chair or the like. The sectional view illustrated in FIG. 10 shows the bottom bar 128 and the top bar 130 of the back. Nailing and foaming grooves 131 are formed in the bars 128 and 130 by the configuration of the female die 110. The ejectors 122 leave recesses. These recesses are advantageous since they lead to a greater compression of the material and a lower consumption of material. When the frame-shaped back (of which the two bars 128 and 130 are visible) has been molded, the box cover 30 is raised from the bottom box 22 by means of the devices illustrated in FIGS. 1 to 4. The spindles 118 and 120 are subsequently raised in the manner described with reference to FIG. 9. The spindles 120 are raised more rapidly than the spindles 118. The bar 128 is raised somewhat more rapidly than the bar 130. Thus, the molded article is lifted out of the bottom box 22 and at the same time pivoted about its left-hand side or about the bar 130. Thus, friction is prevented between the faces of the male die 108 and the two bars.

FIG. 11 illustrates a further mold comprising a bottom box 22 and a box cover 30. FIG. 11 illustrates the mold in the closed position after the second molding operation. During the molding operation illustrated in FIG. 10, the frame-shaped back having the bars 128 and 130 and side bars (not illustrated) was molded from rigid foam. During the molding operation illustrated in FIG. 11, a layer 138 of semirigid foam is applied to the front side of the back. The layer 138 of semirigid foam is indicated by cross-hatching.

The male and female dies and 112 illustrated in FIG. 10 have been replaced by dies 132 and 136. The female die 132is flatter than the female die 110 and is also provided with projections 134, so that the cavity in the mold is formed for the layer 138 of semirigid foam. The seated person rests his back against this layer. The layer 138 of semirigid foam is crosshatched, while the bars 128 and 130 made from rigid foam are shaded diagonally. The layer 138 of semirigid foam runs into the foam grooves 131 in the bottom bar 128 and the top bar 130 and is thus secured therein. The projections 134 form holes which serve for ventilation and which pass through the layer 138 of the semirigid foam, as illustrated in FIG. 11. Following this second molding operation, the box cover 30 is again raised from the bottom box 22. The spindles 118 and are then raised in the manner described with reference to FIG. 9. The molded article now comprising the elements 128, and 138 is lifted out of the bottom box and simultaneously tilted.

FIG. 12 illustrates the state at the end of a third foaming operation. At the commencement of this foaming operation, the molded article which was previously formed in the mold illustrated in FIG. 11, and which comprises the parts 128, 130 and 138, is placed into the bottom box 22 illustrated in FIG. 12. Male dies 140 are located in this bottom box 22. These dies 140 are higher than the dies 136. Furthermore, the dies 140 located on the left is shorter than the die 136 located on the left in FIG. 11. A die which is lower than the die 132 is located in the top box 30. Protuberances 143 are arranged on the bottom of the bottom box 22. The frame comprising the parts 128, 130 and 138 is placed onto the protuberances 143. Thus, the frame is spaced from the bottom of the mold. By virtue of these measures, a free space is provided around the bars 128 and 130 or the layer 138 of semirigid foam. Soft foam enters this free space during the foaming operation. The soft foam 142 forms a soft layer on the layer 138 of semirigid material on the one hand and, on the other hand, forms a core of soft foam within the bars 128 and 130 or the side bars which are not visible in FIG. 12. The box cover 30 is removed again after the foaming operations. The spindles 118 and 120 are raised and press the finished molded article out of the mold in the manner described.

FIGS. 13 to 17 illustrate different embodiments of frameshaped backs which may be manufactured on the molding apparatus constructed in accordance with the invention. The Figures are to be regarded as diagrammatic plan views of a bottom box and show the actual back 144 having the center opening 146 and the side openings 148 into which the side panels of a chair, or the like, are inserted. This also implies that the end of the back, located on the left in FIGS. 13 to 17, is at the bottom. It will be seen from FIGS. 14 and 15 that the side panels are higher in FIG. 15. FIGS. 16 and 17 show'that the back illustrated in FIG. 17 is extended further downwardly and is also wider. These different embodiments of the back are manufactured by inserting corresponding cores into the bottom box.

FIG. 18 is an exploded illustration of a bottom box 22 and a box cover 30. The box cover 30 has only three sidewalls. The fourth sidewall 152 is in the form of a separate wall and is inserted into the angular pieces 150 which extend vertically from the bottom box. An insert 154 is arranged within the bottom box. The insert 154 forms openings of the kind illustrated at 146 in FIGS. 13 to 17. Furthermore, FIG. 18 illustrates bolting elements or reinforcing profiled bars 156. These bolting elements or reinforcing profiled bars 156 are in the form of angle irons. They reinforce the frame-shaped seat which is formed in the mold illustrated in FIG. 18. Nuts 158 are welded onto the horizontal limbs of the reinforcing profiles 156. In the illustrated embodiment, threaded bolts are screwed into the nuts 158 and hold the feet of the seat, or the like. The reinforcing profiled bars 156 are held by spindles 160 during the molding operation. The spindles 160 terminate in threaded lugs 162, as illustrated in FIG. 19. The spindles 160 are turned by a drive illustrated in FIG. 9. After the reinforcing profiled bars 156 have been placed into the bottom box or onto the spindles 160, the spindles 160 are turned in a direction in which the threaded lugs 162 are screwed into the nuts 158. This fulfills a twofold purpose. On the one hand, the reinforcing bars are held and, on the other hand, the nuts 158 are prevented from being filled, with foam material during the molding operation. At the same time, the smooth, cylindrical stems of the spindles 160 prevent foam material from entering through bores through which the threaded bolts are guided to the nuts 158. The spindles 160 are turned in one direction to secure the reinforcing profiles, while they are turned in the other direction to remove the finished molded article after the molding operation. The molded article isthus lifted slightly until the threaded lugs 162 have been screwed out of the nuts 158.

FIG. 18 illustrates further bores 164 in the vertical limbs of the reinforcing bars 156. These bores 164 also have to be kept free from foam material as well as through bores which lead from the inside edge of the seat to the bores 164. The devices illustrated in FIG. are used for this purpose. A plurality of guide bushes 166 are welded to the inside of the insert 154. Pins 168 are located in these bushes. The pins 168 are connected to two-arm levers 170 which are hinged in supports 172 on the bottom 114 of the bottom box by way of further levers. As illustrated in FIG. 20, two guide bushes 166 and thus two levers 170 are located one behind the other. The two levers are connected by a connecting rod 174. Thus, by pulling this single connecting rod 174,-the two levers 170 can be pivoted and the two pins 168 can be inserted (on the right in FIG. 20) into the bores 164 or withdrawn (on the left in FIG. 20 from the bores 164.

In practice, the threaded lugs 164 are first screwed into the nuts 158. The pins 168 are then inserted into the bores 164. The operation is reversed after the foaming or molding operation.

An embodiment of a bottom box is illustrated in FIG. 21 and is used for molding a back of a chair, or the like. It is immaterial to the invention whether a seat, a back, or a different part is to be manufactured. The description and the drawings are intended only to show that the molding apparatus constructed in accordance with the invention can be modified in many different ways. FIG. 21 illustrates the insert 176 which forms the opening in the frame-shaped back. FIG. 21 also illustrates reinforcing profiled bars 178. Inserts 180 are inserted into openings in one limb of the reinforcing profiles 178. The

inserts 180 are hollow which means that the inserts 180 and a corresponding space in front of the insert has to be maintained free from foam material. The inserts 180 also have to be held in a specific position during the molding operation. For this purpose, pins 168 are inserted into the inserts 180 in the same manner as in the embodiment illustrated in FIG. 20. The pins slide into guide bushes 166. They are moved by levers 170. The levers are pivotable about a vertical axis and their movement is limited by stops 182.

Threaded bores 184 are also provided in the reinforcing bars 178. When the chair, or the like, is being assembled. the seat and the back are held together by screws which are screwed into the threaded bores 184. To prevent the threaded bores 184 and the space'(seen in the direction towards FIG. 20) located therebelow from being filled with foam material a spindle provided with a threaded lug is screwed into the bores 184. This spindle is illustrated diagrammatically at 186. Basically, it correspondsto the spindle 160 which was illustrated in detail in FIG. 19.

In the same manner as during the manufacture of the seat, the reinforcing bars 178 are fixed and held by screwing the. spindles into the bores 184 and by inserting the pins into the inserts 180. After the molding operation, the back is first raised by slightly turning the spindles 186. It may then be entirely removed from the bottom box by screwing up the spindles 118 or 120.

A mold comprising a bottom box 22 and a box cover 30 is illustrated diagrammatically in FIGS. 23 and 24 and is used for foaming cushions 194. Such cushions should be particularly soft and resilient. In accordance with the invention, cavities or airspaces are foamed into them for this purpose. For this purpose, oval male dies and 188 or rods 192 are secured to the bottom of the bottom box 22 and/or the cover 30 of the top box.

When the mold is closed, each die 188 in a row secured to the bottom box 22 is located adjacent a core secured to the box cover, etc. Thus, the cores in the different rows are stag gered. This is illustrated in FIG. 23. The openings which have been formed by the dies secured to the top box are designated 196, and the openings which have been formed by the dies secured to the bottom box are designated 198. This staggering of the dies in the separate rows facilitates opening the mold. If the dies 188 secured to the bottom box and to the box cover were located directly one behind the other, the soft foam 194 would be greatly compressed when opening ,the mold if the largest diameters of the dies were moved past one another. This compression of the soft foam 194 could lead to the destruction of the latter. In addition to the cavities formed by the oval dies 188, the rods 192 form additional, elongate cavities which result in the good ventilation of the cushion.

FIG. 25 illustrates a threaded sleevelike member 200 having a wide end flange. The member 200 can be foamed directly into a back or a seat and is fixed at a desired position by a spindle 160 and a threaded lug 172 illustrated in FIG. 19.

I claim:

1. In a molding apparatus having a stand supporting a mold, the mold including a mold bottom box and a cover for said box, the improvement of a vertical guide provided on said stand and mounting said mold, reinforcing profiled bars, means for locating said profiled bars in said mold, means for separating said locating means from said reinforcing profiled bars thereby allowing for the removal of a molded article having said profiled bars embedded therein and drive means for moving said mold box cover between a first position in which the cover closes said mold box and a second position in which the mold box cover lies displaced from said mold box in a mold open position.

2. A molding apparatus as set forth in claim 1, wherein the stand includes a plurality of hollow support members, a rod telescopically received in each hollow support member, a top frame connected to the top ends of the rods to which the mold box cover is secured so as to be interchangeable, a bottom frame being provided which is located at about half the height v01023 OIOI of the hollow supports, and holding devices arranged on the bottom frame to receive the mold box in an interchangeable manner.

3. A molding apparatus as set forth in claim 2 wherein lazy tongs are hinged to the two sides of the top and bottom frames, one end of each bar of each lazy tong being hinged to the respective top and bottom frames, a horizontal guide being provided on the bottom and the top frame for the other free end of each bar, the horizontally displaceable bottom ends of the bars being interconnected by a rod attached to said drive means.

4. A molding apparatus as set forth in claim 1 wherein said drive means comprises a double-acting pneumatic cylinder.

5. A molding apparatus as set forth in claim 3 wherein a flap is provided on the wall of the mold box located between the fixedly hinged bottom ends of the, lazy tong bars which flap is hinged at its base, arcuate links connecting the top end of the flap to a pair of the bars of the lazy tongs the bottom ends of which are hinged to the bottom frame adjacent the flap, one end of the arcuate links being hinged to the flap and the other end being provided with a slotted hole a pin mounted on said bar and arranged to cooperate with said slotted hole.

6. A molding apparatus as set forth in claim 1 wherein cooperating latches are provided on both the top frame and on the mold bottom box.

7. A molding apparatus as set forth in claim 2 wherein a cam is mounted on each side of the top frame and wherein traverses connect the hollow supports on either side, a cam plate being rotatably secured to each traverse which is capable when turned of swinging below the cam to raise the latter, the cam plates being connectable to respective cam control rods, a transverse rod interconnecting said cam control rods so that, by depressing the transverse rod, the cam plates are turned in such a manner that the cams are lifted to open the mold, the cam plates being biassed into a normal position by respective springs attached thereto.

8. A molding apparatus as set forth in claim 3 wherein said drive means comprises a double acting pneumatic cylinder and wherein a rod connecting the displaceable bottom ends of opposite bars of the lazy tongs is arranged parallel to the pneumatic cylinder, the piston rod of the pneumatic cylinder being connected to one end of each of two levers the other ends of which are connected to the bottom frame and the rod respectively, so that the rod is pushed away and the mold is closed when the pneumatic cylinder is actuated and the piston rod extended, and the rod is pulled in and the mold is opened when the piston rod is retracted.

9. A molding apparatus as set forth in claim 8 wherein the two levers are located in a straight line and at right angles to the piston rod when the piston rod is extended and the mold is closed.

10. A moulding apparatus as set forth in claim 7 wherein the pneumatic cylinder is attached to two bars one end of each bar being hinged to the pneumatic cylinder the other ends of the bars being hinged to the outer ends of said levers, the bars thus being hinged to the bottom frame and the rod respectively.

ll. A molding apparatus as set forth in claim 1 wherein the mold box and the mold box cover each comprises a bottom or top wall and two sidewalls, the sidewalls on the bottom box and on the box cover being secured on opposite sides so that the sides of the molding box are alternately closed by a sidewall from above and below, an angular piece being mounted on the bottom of the mold bottom box and on the top wall of the box cover at the sides of the mold bottom box and the box cover not closed by a sidewall, which angular piece overlaps the associated sidewall when the mold is in a closed position.

12. A molding apparatus as set forth in claim 1 wherein lifting and removing ejectors are reciprocably mounted in the bottom of the mold box.

13. A molding apparatus as set forth in claim 12, wherein spindles are provided which receive the lifting and removing ejectors said spindles being guided in vertical guide bushes and coupled to a drive source.

14. A molding apparatus as set forth in claim 13. wherein the spindles are threaded and provided with sprocket wheels which are rotatable by way of a chain to impart a reciprocable movement to said spindles.

15. A molding apparatus as set forth in claim 14 wherein the chain is rotated by a ratchet mounted on one of said spindles.

16. A molding apparatus as set forth in claim 14 wherein the chain is rotated by a pneumatic cylinder which is operatively connected thereto. 1

17. A molding apparatus as claimed in claim 14, wherein the spindles have different pitches.

18. A molding apparatus as set forth in claim 1 wherein the mold box cover is closed on three sides, the mold bottom box having a pair of vertical guides for receiving a sidewall at its side corresponding with the free side of said mold box cover.

19. A molding apparatus as set forth in claim 1 wherein said means for locating said profile bars include spindles and wherein said spindles are guided vertically in the bottom of the mold bottom box, the spindles having threaded lugs on their top ends, which are arranged to engage into corresponding threaded bores which are provided in a reinforcing profiled bar which is placed into the mold.

20. A molding apparatus as set forth in claim 19 wherein the portions of the spindles located in the molding box are smooth and cylindrical, the spindles being reciprocable by a chain drive as claimed in claim 14.

21. A molding apparatus as set forth in claim 1 wherein an insert having a shape corresponding to an opening to be formed in the molded article is mounted on a bottom wall of the molding box, bores in said insert for receiving pins corresponding to through holes to be formed in the molded article.

22. A molding apparatus as set forth in claim 21 wherein the pins are guided in guide bushes secured on the inside of the insert and wherein the inner ends of the pins are hinged to twoarm levers, one end of each lever being pivotably held in a support on the bottom of the mold box, the free ends of the two-arm levers being provided with a handle.

23. A molding apparatus as set forth in claim 22 wherein the two-arm levers located in alignment on one side of the insert are interconnected by a connecting rod which is in the fonn of a common actuating handle.

24. A molding apparatus as set forth in claim 22, wherein the levers are pivotable in a horizontal plane about a vertical axis.

25. A molding apparatus as set forth in claim 1 wherein oval dies are arranged substantially in the center plane of the mold and are held on rods on the mold bottom box.

26. A molding apparatus asset forth in claim 1 wherein oval dies are arranged substantially in the center plane of the mold and are held on the mold box cover.

27. A molding apparatus as set forth in claim 1 wherein oval dies are arranged substantially in the center plane of the mold and are held both on the mold bottom box and on the mold box cover.

28. A molding apparatus as set forth in claim 27 wherein rows of dies are secured alternately to the mold box and to the box cover, the dies in adjacent rows being staggered. 

1. In a molding apparatus having a stand supporting a mold, the mold including a mold bottom box and a cover for said box, the improvement of a vertical guide provided on said stand and mounting said mold, reinforcing profiled bars, means for locating said profiled bars in said mold, means for separating said locating means from said reinforcing profiled bars thereby allowing for the removal of a molded article having said profiled bars embedded therein and drive means for moving said mold box cover between a first position in which the cover closes said mold box and a second position in which the mold box cover lies displaced from said mold box in a mold open position.
 2. A molding apparatUs as set forth in claim 1, wherein the stand includes a plurality of hollow support members, a rod telescopically received in each hollow support member, a top frame connected to the top ends of the rods to which the mold box cover is secured so as to be interchangeable, a bottom frame being provided which is located at about half the height of the hollow supports, and holding devices arranged on the bottom frame to receive the mold box in an interchangeable manner.
 3. A molding apparatus as set forth in claim 2 wherein lazy tongs are hinged to the two sides of the top and bottom frames, one end of each bar of each lazy tong being hinged to the respective top and bottom frames, a horizontal guide being provided on the bottom and the top frame for the other free end of each bar, the horizontally displaceable bottom ends of the bars being interconnected by a rod attached to said drive means.
 4. A molding apparatus as set forth in claim 1 wherein said drive means comprises a double-acting pneumatic cylinder.
 5. A molding apparatus as set forth in claim 3 wherein a flap is provided on the wall of the mold box located between the fixedly hinged bottom ends of the lazy tong bars which flap is hinged at its base, arcuate links connecting the top end of the flap to a pair of the bars of the lazy tongs the bottom ends of which are hinged to the bottom frame adjacent the flap, one end of the arcuate links being hinged to the flap and the other end being provided with a slotted hole a pin mounted on said bar and arranged to cooperate with said slotted hole.
 6. A molding apparatus as set forth in claim 1 wherein cooperating latches are provided on both the top frame and on the mold bottom box.
 7. A molding apparatus as set forth in claim 2 wherein a cam is mounted on each side of the top frame and wherein traverses connect the hollow supports on either side, a cam plate being rotatably secured to each traverse which is capable when turned of swinging below the cam to raise the latter, the cam plates being connectable to respective cam control rods, a transverse rod interconnecting said cam control rods so that, by depressing the transverse rod, the cam plates are turned in such a manner that the cams are lifted to open the mold, the cam plates being biassed into a normal position by respective springs attached thereto.
 8. A molding apparatus as set forth in claim 3 wherein said drive means comprises a double acting pneumatic cylinder and wherein a rod connecting the displaceable bottom ends of opposite bars of the lazy tongs is arranged parallel to the pneumatic cylinder, the piston rod of the pneumatic cylinder being connected to one end of each of two levers the other ends of which are connected to the bottom frame and the rod respectively, so that the rod is pushed away and the mold is closed when the pneumatic cylinder is actuated and the piston rod extended, and the rod is pulled in and the mold is opened when the piston rod is retracted.
 9. A molding apparatus as set forth in claim 8 wherein the two levers are located in a straight line and at right angles to the piston rod when the piston rod is extended and the mold is closed.
 10. A moulding apparatus as set forth in claim 7 wherein the pneumatic cylinder is attached to two bars one end of each bar being hinged to the pneumatic cylinder the other ends of the bars being hinged to the outer ends of said levers, the bars thus being hinged to the bottom frame and the rod respectively.
 11. A molding apparatus as set forth in claim 1 wherein the mold box and the mold box cover each comprises a bottom or top wall and two sidewalls, the sidewalls on the bottom box and on the box cover being secured on opposite sides so that the sides of the molding box are alternately closed by a sidewall from above and below, an angular piece being mounted on the bottom of the mold bottom box and on the top wall of the box cover at the sides of the mold bottom box and the box cover not closed by a sidewall, which angular piece overLaps the associated sidewall when the mold is in a closed position.
 12. A molding apparatus as set forth in claim 1 wherein lifting and removing ejectors are reciprocably mounted in the bottom of the mold box.
 13. A molding apparatus as set forth in claim 12, wherein spindles are provided which receive the lifting and removing ejectors said spindles being guided in vertical guide bushes and coupled to a drive source.
 14. A molding apparatus as set forth in claim 13, wherein the spindles are threaded and provided with sprocket wheels which are rotatable by way of a chain to impart a reciprocable movement to said spindles.
 15. A molding apparatus as set forth in claim 14 wherein the chain is rotated by a ratchet mounted on one of said spindles.
 16. A molding apparatus as set forth in claim 14 wherein the chain is rotated by a pneumatic cylinder which is operatively connected thereto.
 17. A molding apparatus as claimed in claim 14, wherein the spindles have different pitches.
 18. A molding apparatus as set forth in claim 1 wherein the mold box cover is closed on three sides, the mold bottom box having a pair of vertical guides for receiving a sidewall at its side corresponding with the free side of said mold box cover.
 19. A molding apparatus as set forth in claim 1 wherein said means for locating said profile bars include spindles and wherein said spindles are guided vertically in the bottom of the mold bottom box, the spindles having threaded lugs on their top ends, which are arranged to engage into corresponding threaded bores which are provided in a reinforcing profiled bar which is placed into the mold.
 20. A molding apparatus as set forth in claim 19 wherein the portions of the spindles located in the molding box are smooth and cylindrical, the spindles being reciprocable by a chain drive as claimed in claim
 14. 21. A molding apparatus as set forth in claim 1 wherein an insert having a shape corresponding to an opening to be formed in the molded article is mounted on a bottom wall of the molding box, bores in said insert for receiving pins corresponding to through holes to be formed in the molded article.
 22. A molding apparatus as set forth in claim 21 wherein the pins are guided in guide bushes secured on the inside of the insert and wherein the inner ends of the pins are hinged to two-arm levers, one end of each lever being pivotably held in a support on the bottom of the mold box, the free ends of the two-arm levers being provided with a handle.
 23. A molding apparatus as set forth in claim 22 wherein the two-arm levers located in alignment on one side of the insert are interconnected by a connecting rod which is in the form of a common actuating handle.
 24. A molding apparatus as set forth in claim 22, wherein the levers are pivotable in a horizontal plane about a vertical axis.
 25. A molding apparatus as set forth in claim 1 wherein oval dies are arranged substantially in the center plane of the mold and are held on rods on the mold bottom box.
 26. A molding apparatus as set forth in claim 1 wherein oval dies are arranged substantially in the center plane of the mold and are held on the mold box cover.
 27. A molding apparatus as set forth in claim 1 wherein oval dies are arranged substantially in the center plane of the mold and are held both on the mold bottom box and on the mold box cover.
 28. A molding apparatus as set forth in claim 27 wherein rows of dies are secured alternately to the mold box and to the box cover, the dies in adjacent rows being staggered. 